Commitments and Contingencies - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) ft²	Jun. 30, 2019 USD ($)
Operating Leased Assets [Line Items]
Lease costs	$ 0.1	$ 0.3	$ 0.1	$ 0.3
Operating lease, weighted average remaining lease term	7 months 6 days		7 months 6 days
Operating lease, weighted average discount rate	5.50%		5.50%
Newton, MA
Operating Leased Assets [Line Items]
Rentable office space under operating lease | ft²			7,795
Base rent for office space			$ 0.3
Operating lease expiration date			Dec. 31, 2020
Sudbury, MA
Operating Leased Assets [Line Items]
Rentable office space under operating lease | ft²			7,564
Base rent for office space			$ 0.2
Operating lease expiration date			Feb. 28, 2021